I've split some with a maul that fell apart as easy as sub-freezing red oak. And some that's rivaled big rock maple, crotch popple, or even elm.
The tougher stuff, I've noticed, had bark that seemed blighted. The healthier, smmoth-bark beech seemed to split easier.
Beech is a fascinating species. It actually has tropical roots and slowly made its way north thousands of years after the last Ice Age. I've heard that that's why it clings to its leaves in winter. Still trying to figure out this change in season thing. The other theory I've heard is that its a defense against browsing animals. The deer nibble the leaves instead of the buds.